Often a common question asked is about the ports that need to be open on a firewall/router device to allow the VPN to work with SBS 2003 and SBS 2008. Each router has it’s own configuration interface and as such may have extra options that need to be changed in order for the VPN to work correctly.
In order to have VPN run correctly, you need to enable it on SBS 2003 or SBS 2008 via the relevant wizard from the SBS console. Following that you need to ensure that Port 1723 is opened to allow inbound traffic to the SBS server.
If you have a more advanced firewall then you will also need to specify the protocol that needs to be open on Port 1723 and that is Protocol 47 (GRE).
Some routers also have a configuration option specifically to allow PPTP VPN Pass-through, so keep an eye out for these options in case you are having problems with your PPTP VPN on SBS.